Polar Opposites (But Maybe Not So Much)
Like the south and north, or the black and the white. Naruto and Sasuke are opposites. One scorned and the other adored. Both were alone; one by choice, the other by consequential circumstances.
They both had their hardships, the Kyuubi or Itachi, respectively. Neither had a family, but eventually they had each other. Both are powerful and independent, destined for their paths that no one can deter them from. On a power trip (or is it on a trip for power?).
Sasuke knows all the scars that mar Naruto's tan skin. After hours of tracing them with his tongue, lips and hands, he really should. Naruto knows all of Sasuke's buttons and knows just how to push them. After all the time he spent pissing off the raven, that isn't much of a surprise. The secret is, Sasuke really doesn't care too much (as long as Naruto is still in bed with him the next morning).
They've both seen each other at their best and worst (and scariest). Both mentally and physically, they know each other inside out. Naruto has seen Sasuke in the morning, before he's had his coffee. And Sasuke's seen Naruto before he's showered and dressed, still stick and grimy from last night's activities. But Naruto has also seen Sasuke when his team of Genin finally performs that new jutsu. Sasuke has witnessed that smile that spreads over the blonde's face when Sakura's children come over to play with their own Maaya and Sachie. Sakura's daughter, Takeko, and their Sachie kind of remind Naruto of himself and Sasuke.
They've been through more than most couples could ever dream of. Chuunin exams and Orochimaru, and hey, they did have Kakashi as a teacher. Even now, they're partners and are sent out on missions together, whether it's because of their almost psychic ability to sense what the other is going to do or because of their reluctance (refusal) to work with anyone else, maybe it's both. The point is, they have seen each other hurt and nearly killed. They've seen each other kill enemy ninja and hold no delusions about how much power both possess. They know that if they ever seriously fought, like the time in the valley before Sasuke left, they would cause nearly irreversible destruction and would probably kill anyone but each other. But in the end both would die of exhaustion. (So it's a rather good thing they put their anger in to insults and sex rather than battles to the death.)
The two have lived through the worst conquests and ideas. Sai and Gaara and Sakura and Ino, and even Neji that one time; never again though, because they're both jealous bastards. When they go to a bar or a party or wherever, Sasuke rarely lets Naruto out of his arms. And Naruto isn't really trying to get away, because, c'mon the fangirls have only gotten stronger since their days at the academy.
No one has ever really been able to calm either of them down. When Sasuke used to get angry, he would train and brood, or sometimes he would clean. And when Naruto got pissed off, he would pulls the most moronic pranks where he was mostly guaranteed to get caught and punished. Basically, they both tried to forget by keeping themselves busy. But now, if Naruto comes home angry after a solo mission, Sasuke just holds him until Naruto falls asleep. And if Sasuke's patience has been tried within an inch of its life, Naruto puts Sachie and Maaya to bed by himself and then blows Sasuke until the raven passes out from extensive orgasms. (And that right there, ladies and gentlemen, is true love.)
Both Naruto and Sasuke are too damn stubborn for their own good. (And, poor Iruka, both Sachie and Maaya carry that trait as well.) Neither will ever apologize, and neither will ever ask for an apology. Naruto will never beg for anything or ask for anything that is completely unavoidable. To Sasuke, giving in to Naruto on almost any grounds (sex being that neutral zone where any thing goes, thank Kami) is a sign of weakness. Naruto agrees completely, so he never agrees with Sasuke if it goes against his opinion or beliefs. (And if Naruto is apathetic toward an idea, he'll usually oppose Sasuke anyway, just to piss him off. Because anger breeds not good, but a-fucking-mazing sex.) But if agree on something (a miracle in and of itself) then everyone might as well just go home, because there's no possible way to get through to either of them. Their agreement on any subject is a force to be reckoned with.
Another thing, no one can ever screw with either of them. Upsetting either Naruto or Sasuke will have the other out for the poor soul's blood. It's really generally accepted as their thing. Ticking each other off if like their foreplay or something. And no one, ever, purposely argues with either man. For that would be both stupid and lead to the bloody and painful removal of necessary appendages. And anyway, if everyone messed with Naruto and Sasuke half as much as they did each other, Naruto and Sasuke's rage would be such that bodies would be littering the streets of Konoha.
Naruto and Sasuke were both from opposite sides of the track. Sasuke had money and a family (at one point, at least) and he had people falling over themselves to his friend (hell, he still has that. He was the golden child of the academy that could and would do no wrong. He excelled at everything from jutsus to weaponry and even got all the girls (not that he ever paid that much any attention). Naruto was the problem child with no family and little money. He was shunned by his village for reasons he didn't really understand at the time. He was the dead-last at the academy and acted out to receive attention. The girls wouldn't give him the time of day (and he actually sort of kind of cared). And no matter how much he worked and studied and trained, he could barely manage the simplest of jutsus. Sasuke graduated the academy at the top of the class and Naruto barely graduated. Both of the lives were far from perfect and were rather lonely, so both swore that Sachie and Maaya's lives would be completely better than theirs. The girls wouldn't grow up orphans.
Naruto and Sasuke are polar opposites, well kind of. Maybe they're that grey area where white meets black. Where good meets evil and is just power. Where the north and south attract like magnets. (Where Sasuke's cock fits just right in Naruto's ass.)